yeah I like that. Keep it simple. Too busy on a sticker is too distracting.
I do think the forum banner would print ok on a stubby holder - photo type prints are common enough. But it would need to be very truncated as the total length is quite small, not banner length (1 expanda plus logo close to it is probably about all would fit)
However, for my two cents, whenever I used to do promotion or marketing stuff etc in my old job, I always needed to be conscious of brand identification. Although I like Andreas design, it is not the website's 'identification',and Moderator/owner of forum should consider this aspect - ie we don't usually see companies using two differing logos. No, this isn't a company, but we are talking a group identification by providing merchandise. So, looking up at the top banner, forgetting the colour background, what I see is a grey box with yeloow/orage border and text. That is really the 'identifiable' logo - whether intentional or not. Therefore, I think the next question mod/owner should ask is 'should that also be modified to match the merchandise' or alternatively 'should the merch be the grey box with yellow/orange border and text'?